Process for producing crystals of a diazabicyclooctane derivative

ABSTRACT

A process for producing crystals of a compound represented by the following formula (I): 
     
       
         
         
             
             
         
       
     
     by crystallizing the compound from an aqueous solution containing the compound and an inorganic salt, such as sodium chloride. Such crystals can be subjected to lyophilization to provide a lyophilized composition having a desirable storage stability.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of U.S. application Ser.No. 15/532,281, filed Jun. 1, 2017, which is a U.S. National Phaseapplication of International Application No. PCT/JP2015/084094, filedDec. 4, 2015, which is based upon and claims the benefit of priorityfrom prior Japanese Patent Application No. 2014-246425, filed Dec. 5,2014. The entire contents of all the above-identified applications areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a process for producing crystals of adiazabicyclooctane derivative represented by formula (I), as well as acomposition and lyophilized preparation of said derivative, and aprocess for producing the same.

BACKGROUND

The novel diazabicyclooctane derivative represented by formula (I)below: (2S ,5R)-N-(2-aminoethoxy)-7-oxo-6-(sulfooxy)-1,6-diazabicyclo[3.2.1]octane-2-carboxamide (hereinafter referred to as “Compound (I)”)is a β-lactamase inhibitor, and disclosed in WO2013/180197 (PatentDocument 1).

A method for obtaining a crystalline lyophilized composition has beendisclosed in which a solution of a chemical substance is frozen at aprescribed temperature, and heated to a prescribed temperature, afterwhich the temperature is kept constant (hereafter referred to as a heattreatment step) (Patent Document 2).

Patent Document 3 and Patent Document 4 disclose that an inorganic saltmay be added to an solution of a chemical substance in lyophilizationmethods that involve a heat treatment step.

Patent Document 5 discloses a method for obtaining a crystallinelyophilized composition by subjecting an aqueous solution of a chemicalsubstance containing 2 to 10% (v/v) of a C₁₋₃ alcohol or acetone to alyophilization procedure that involves a heat treatment step.

Patent Document 6 discloses crystals of compound (I) and productionprocess thereof.

PRIOR ART DOCUMENTS Patent Documents

-   [Patent Document 1] WO2013/180197-   [Patent Document 2] Japanese Examined Patent Publication No. Hei    03-74643-   [Patent Document 3] Japanese Patent No. 2843444-   [Patent Document 4] Japanese Patent No. 2767171-   [Patent Document 5] Japanese Examined Patent Publication No. Sho    60-19759-   [Patent Document 6] WO 2015/053297

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Our studies have shown that when compound (I) is lyophilized usingstandard conditions that include a freezing step, followed by a step ofdrying under reduced pressure, compound (I) becomes amorphous, and thatits chemical stability is significantly lower than the crystallinestate, making it difficult to obtain a lyophilized composition havinggood storage stability. In light of producing and distribution, a stablelyophilized composition of compound (I) has been highly sought after.

However, lyophilization of an aqueous solution of compound (I) using themethod of Patent Document 2 did not yield a crystalline lyophilizedcomposition.

The examples of Patent Document 3 show that a crystalline lyophilizedcomposition can be obtained whether or not an inorganic salt is added,which means that addition of an inorganic salt is not essential forcrystallization. Moreover, it is disclosed that, under standardlyophilization conditions that involve no heat treatment step, additionof an inorganic salt leads to an increase in amorphous content, therebyadversely affecting crystallization. Furthermore, in Patent Document 4,a heat treatment step is incorporated without exception and there are noexamples where an inorganic salt is added. The method of Patent Document5 is not desirable as an industrial producing process, as there isconcern over residual solvents.

As seen from the above, no methods have been found for obtaining acrystalline lyophilized composition under lyophilization conditions thatdo not involve a heat treatment step or addition of an organic solvent.

On the other hand, the process of Patent Document 6 could not providecrystals of compound (I) sufficiently before an aqueous solutioncontaining compound (I) is purified once by a column and the like.

Further, it is problem to obtain a single crystalline form and inparticular stable form I by controlling polymorphism.

Therefore, a process for producing crystals of compound (I) easily in anindustrial scale, and further a process for producing a singlecrystalline form and in particular crystalline form I of compound (I)has been highly sought after.

The objects of the present invention are to provide a process forproducing crystals, especially a single crystalline form and inparticular stable crystalline form I of compound (I) easily in anindustrial scale, and a stable lyophilized composition of compound (I).

Means for Solving the Problems

As a result of extensive research on developing a lyophilizedcomposition of compound (I) having good storage stability, the presentinventor has found that subjecting an aqueous solution containingcompound (I) and an inorganic salt such as sodium chloride tolyophilization crystallizes the compound (I), and consequently yields alyophilized composition having good storage stability wherein thecompound (I) is crystalline, especially a single crystalline form and inparticular stable crystalline form I, and has further found thatcrystals, especially a single crystalline form and in particular stablecrystalline form I of compound (I) can be obtained from said aqueoussolution without lyophilization, thereby completing the presentinvention.

The present invention relates to a process for producing crystals ofcompound (I), comprising crystallizing compound (I) from an aqueoussolution containing compound (I) and an inorganic salt such as sodiumchloride.

The present invention also relates to a process for producing alyophilized composition comprising compound (I), comprisingcrystallizing compound (I) by said process for producing crystals ofcompound (I); a process for producing a lyophilized compositioncomprising compound (I), comprising crystallizing compound (I) bysubjecting an aqueous solution containing compound (I) and an inorganicsalt such as sodium chloride to lyophilization; as well as a lyophilizedcomposition containing crystals of compound (I) and an inorganic saltsuch as sodium chloride. The lyophilized composition of the presentinvention is obtainable by said process for producing a lyophilizedcomposition.

In the present invention, for example, compound (I) is crystallized by ageneral method including a method wherein a seed crystal is added asnecessary to an aqueous solution containing compound (I) and aninorganic salt such as sodium chloride, and then a poor solvent is addedthereto. Or, compound (I) is crystallized by subjecting an aqueoussolution containing compound (I) and an inorganic salt such as sodiumchloride to lyophilization. The presence of an inorganic salt such assodium chloride allows crystals of compound (I), especially, samecrystalline form I as one disclosed in Patent Document 6 to be obtained,thereby drastically improving storage stability compared to amorphousstates.

Crystalline form I of the present invention is the same as crystallineform I of Patent Document 6, and shows a characteristic peak pattern inpowder X-ray diffraction as shown in Table 1 and FIG. 3 below. In thepresent invention, the powder X-ray diffraction is measured according toa method mentioned in Test example 1.

TABLE 1 Powder X-ray data Powder X-ray diffraction of Crystalline form IPeak position 2θ Latticer spacing (d) Relative intensity (CuKα) Å I/IO12.04 7.34 13 15.64 5.66 53 16.02 5.53 26 16.70 5.30 58 17.66 5.02 4919.02 4.66 100 20.30 4.37 46 20.74 4.28 11 21.88 4.06 10 24.16 3.68 1124.56 3.62 15 25.66 3.47 18 26.54 3.36 17 26.96 3.30 13 28.18 3.16 1228.72 3.11 14 29.44 3.03 16 29.86 2.99 13 35.90 2.50 10

Further, in the present invention, an aqueous solution containingcompound (I) and an inorganic salt such as sodium chloride is subjectedto lyophilization. For example, it is lyophilized using standardconditions that include a freezing step, and a subsequent step of dryingunder reduced pressure. That is, the present invention also relates to aprocess for producing a lyophilized composition comprising compound (I),comprising subjecting an aqueous solution containing compound (I) and aninorganic salt such as sodium chloride to a freezing step, andsubjecting a frozen product obtained in said freezing step to a step ofdrying under reduced pressure. The presence of an inorganic salt such assodium chloride allows a lyophilized composition to be obtained whereinthe compound (I) is crystalline and especially crystalline form I,thereby drastically improving storage stability compared to amorphousstates.

In the present invention, a lyophilized composition wherein the compound(I) is crystalline can be obtained without involving a heat treatmentstep or a refreezing step between the steps of freezing and drying underreduced pressure. That is, in the process of the present invention forproducing a lyophilized composition, no heat treatment or refreezing ofa frozen product obtained in said freezing step may be performed. Ingeneral, lyophilization is a producing process that requires a longtime. Methods are known for obtaining a crystalline lyophilizedcomposition that involve a heat treatment step and a refreezing stepbetween the steps of freezing and drying under reduced pressure, butthere is a problem of low productivity due to further extended producingtimes. In the present invention, a lyophilized composition wherein thecompound (I) is crystalline can be obtained without involving a heattreatment step or a refreezing step between the steps of freezing anddrying under reduced pressure, thereby increasing productivity comparedto conventional methods.

In the present invention, a heat treatment step and a refreezing stepmay be incorporated between the steps of freezing and drying underreduced pressure. That is, the present invention also relates to saidprocess for producing a lyophilized composition comprising compound (I),further comprising subjecting the frozen product obtained in saidfreezing step to a heat treatment step, subjecting a heat-treatedproduct obtained in said heat treatment step to a refreezing step, andsubjecting a refrozen product obtained in said refreezing step to saidstep of drying under reduced pressure. The incorporation of a heattreatment step further improves the crystallization efficiency ofcompound (I).

Effects of Invention

In the present invention, crystals of compound (I) can be obtained bycrystallization from an aqueous solution containing compound (I) and aninorganic salt without previous purification of compound (I) with acolumn, etc., and thus, crystals, especially a single crystalline formand in particular stable crystalline form I of compound (I) can bepredominantly produced easily in an industrial scale. Further, in thepresent invention, a lyophilized composition wherein compound (I) iscrystalline, especially a single crystalline form and in particularcrystalline form I can be obtained by lyophilization from an aqueoussolution containing compound (I) and an inorganic salt, and then alyophilized preparation of compound (I) having good storage stabilitycan be provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 Powder X-ray diffractogram of the lyophilized compositionobtained in Example 1a.

FIG. 2 Powder X-ray diffractogram of the lyophilized compositionobtained in Example 1b.

FIG. 3 Powder X-ray diffractogram of the crystals obtained in Example2b.

FIG. 4 Powder X-ray diffractogram of the lyophilized compositionobtained in Comparative example 1.

FIG. 5 Powder X-ray diffractogram of sodium chloride.

MODE FOR CARRYING OUT THE INVENTION

Any inorganic salt that can be added to a parenteral injection may beused in the present invention, and sodium chloride, magnesium chloride,calcium chloride, potassium chloride, ammonium chloride, sodium bromide,calcium bromide, potassium bromide, tetrabutyl ammonium bromide,magnesium sulfate, sodium iodide, potassium iodide, sodiumhydrogenphosphate, sodium acetate, sodium citrate, sodium tartrate,sodium glutamate, Rochelle salt (potassium sodium tartrate), etc. areexemplified. Sodium chloride, magnesium chloride, magnesium sulfate,sodium citrate, sodium glutamate and Rochelle salt (potassium sodiumtartrate) are preferable in terms of crystallization efficiency. It wasconfirmed that crystalline form I of compound (I) can be obtained byusing any of these inorganic salts. Sodium chloride is particularlypreferable. The amount of the inorganic salt of the present inventioncontained in a lyophilized composition or a medicinal preparation mayvary, but is preferably 0.1 to 10 molar equivalents, and more preferably1 to 2 molar equivalents to compound (I). This is because adding theamount that is too large or too small would result in a decrease incrystallization efficiency, and affect the stability of the preparation.

Further, in case of crystallization from an aqueous solution containingcompound (I) and an inorganic salt, the amount of the inorganic saltcontained in said aqueous solution may vary, but is preferably 0.1 to 10molar equivalents, and more preferably 0.5 to 1.5 molar equivalents tocompound (I).

In the present invention, the concentration of compound (I) in theaqueous solution prior to crystallization or lyophilization is typically1 to 40% (w/w), preferably 2.5 to 20% (w/w), and more preferably 7.5 to10% (w/w). This is because low said concentrations lead to a decrease incrystallization efficiency, thereby affecting the stability of thepreparation, whereas high said concentrations are prone to precipitationfrom oversaturated solutions.

An aqueous solution containing compound (I) and an inorganic salt of thepresent invention may be prepared by dissolving compound (I) and aninorganic salt together in water, or by dissolving either of them inwater to provide a solution, and then dissolving the residual other inthe solution

In the present invention, for example, compound (I) is crystallized byadding a seed crystal as necessary to an aqueous solution containingcompound (I) and an inorganic salt, and then adding a poor solventthereto. Here, as the seed crystal, seed crystals of compound (I) may beused, for example, crystalline forms I of Patent Document 6 may be used.Or, a lyophilized composition obtained by subjecting an aqueous solutioncontaining compound (I) and an inorganic salt to lyophilization may beused as the seed crystal. The amount of the seed crystal used is 0 to20wt % and preferably 0.01 to 2wt %.

Examples of poor solvents include alcohol such as methanol, ethanol1-propanol and isopropanol, acetone, acetonitrile, and tetrahydrofuran,and preferably include alcohol such as methanol, ethanol, 1-propanol orisopropanol. The amount of the poor solvent is adjusted based onsolubility so that isolation loss is 1% or less. For example, the poorsolvent is used at 1 to 10 times, preferably 3 to 7.5 times and morepreferably 5 to 7.5 times, the initial volume of the aqueous solutioncontaining compound (I) and an inorganic salt. The timing of theaddition of poor solvent is not limited. For example, after the mixturehas formed slurry following seeding, the poor solvent is dropped thereinin the case of crystalline form I. Time for the addition of poor solventis not limited, and for example, half an hour or more, and preferablyone hour or more.

In the present invention, compound (I) may be crystallized after controlof the temperature of an aqueous solution containing compound (I) and aninorganic salt.

Stirring time is dependent upon precipitation rate, and stirring iscarried out for 1 hour to 24 hours and preferably for 1 hour to 15hours.

The crystals of compound (I) can be obtained by ordinary filtration,washing and through-flow drying or vacuum drying of the precipitatedcrystals. In the case of solvated crystals, excessive drying is avoidedby using means to controling material temperature, loss on drying,humidified and limited vacuum drying or humidified through-flow drying.

In the present invention, compound (I) may be crystallized by subjectingan aqueous solution containing compound (I) and an inorganic salt tolyophilization. Further, the present invention also relates to a processfor producing a lyophilized composition comprising compound (I),comprising crystallizing compound (I) by subjecting an aqueous solutioncontaining compound (I) and an inorganic salt to lyophilization.

In the present invention, for example, an aqueous solution containingcompound (I) and an inorganic salt is subjected to a conventionallyophilization procedure that includes a freezing step and a step ofdrying under reduced pressure. The refrigeration temperature used forfreezing said aqueous solution varies depending on the concentrations ofcompound (I) and the inorganic salt, but is typically between −60 and−10° C., preferably between −50 and −10° C., more preferably between −50and −15° C. The rate used for freezing may vary, but the freezing steptypically lasts for 0.25 to 5 hours. After freezing, the frozen productobtained in the freezing step may be stored at the refrigerationtemperature for a period of time until the next step of drying underreduced pressure.

The step of drying under reduced pressure to which the frozen productobtained in said freezing step is subjected may be divided into a stepof primary drying (sublimation) and a step of secondary drying(dehumidification). The primary drying step is performed, as is typical,under reduced pressure, and although the temperature to be used cannotbe specified because it is affected by the concentrations of compound(I) and an inorganic salt, it is preferably adjusted to conditions inwhich the temperature of the material does not exceed the collapsetemperature of the frozen product. The drying time cannot be specifiedbecause it varies depending on the temperature used and the scale ofproduction, but this step may typically last for 2 hours to 7 days,preferably 5 hours to 72 hours, while changes in the temperature of thematerial and the degree of vacuum are monitored. The secondary dryingstep is performed, as is typical, under reduced pressure and it may beperformed at a temperature of, for example, 10 to 60° C., preferably 25to 60° C. The drying time cannot be specified because it variesdepending on the temperature used and the scale of production, but thisstep may typically last for 2 to 72 hours, preferably 5 to 20 hours,while changes in the temperature of the material and the degree ofvacuum are monitored.

In the present invention, to improve crystallization efficiency, a heattreatment step and a refreezing step may be incorporated between thefreezing step and the step of drying under reduced pressure, which aredescribed above. The temperature used in heat treatment of the frozenproduct obtained in said freezing step is affected by the concentrationsof compound (I) and an inorganic salt, but this step is performed at atemperature where the material remains frozen, preferably at −40 to 0°C., and more preferably −20 to −4° C. The heat treatment time cannot bespecified because it varies depending on the temperature used and thescale of production, but this step may typically last for 0.5 to 72hours, preferably 1 to 24 hours. The temperature used in the refreezingstep to which a heat-treated product obtained in said heat treatmentstep is subjected is typically −60 to −10° C., preferably −50 to −10°C., more preferably −50 to −15° C. The freezing rate may vary, but thisstep typically lasts for 0.25 to 5 hours. A refrozen product obtained inthe refreezing step is subjected to said step of drying under reducedpressure.

When the crystals and the lyophilized compositions of the presentinvention are used as a medicament, they may be administered as such (asingredients), or may be administered as a conventional medicinalpreparation. Said medicinal preparation may contain a pharmacologicallyacceptable additive such as excipient, lubricant, binder, disintegrant,emulsifier, stabilizer, flavoring agent, diluent or the like, so long asthe additive do not undermine the effects of the present invention.Examples of said medicinal preparation include tablets, capsules,powders, syrups, granules, fine granules, pills, suspensions, emulsions,percutaneous absorption preparations, suppositories, ointments, lotions,inhalants, injections and the like. The crystals and the lyophilizedcompositions of the present invention as well as said medicinalpreparation may be orally or parenterally administered (such asintravenous administration, intramuscular administration,intraperitoneal administration, percutaneous administration,intratracheal administration, intracutaneous administration, orsubcutaneous administration).

In said medicinal preparation of the present invention, in addition tocompound (I), a β-lactamase inhibitor, β-lactam antibiotics may beincorporated. Examples of what may be incorporated include piperacillin,ampicillin, benzylpenicillin, cefoperazone, cefazolin, cefalotin,cefotiam, cefminox, cefmetazole, flomoxef, cefodizime, cefotaxime,ceftriaxone, cefmenoxime, latamoxef, ceftazidime, cefepime, cefozopran,cefpirome, aztreonam, imipenem, doripenem, panipenem, biapenem,meropenem, and their pharmacologically acceptable salts and solvates.

Any additive that can generally be added to injections may, whereappropriate, be incorporated in said injections of the presentinvention. Examples of what may be incorporated for the purpose ofadjusting pH include inorganic acids such as hydrochloric acid andphosphoric acid, and salts thereof, organic acids such as citric acid,malic acid, tartaric acid, and succinic acid, and salts thereof, aminoacids such as arginine, alanine, aspartic acid, histidine, and glycine,and bases such as sodium hydroxide and sodium bicarbonate. Examples ofwhat may be incorporated for the purpose of adjusting osmotic pressureinclude glucose, mannitol, xylitol, sorbitol, sucrose, lactose, maltose,trehalose, and dextran. Furthermore, examples of what may beincorporated for the purpose of improving solubility include polyolssuch as polyethylene glycol and glycerin, and surfactants such aspolysorbates, sorbitan sesquioleate, polyoxyethylene-polyoxypropyleneglycols, and polyoxyethylene hydrogenated castor oils.

EXAMPLES

The following Examples and Comparative examples describe embodiments ofthe present invention in concrete terms, but are not to be construed aslimiting the present invention.

Example 1 A Lyophilized Composition of Compound (I) Example 1a

700 mg of compound (I) and 126.1 mg of sodium chloride were dissolvedinto distilled water, and the total weight was adjusted to 7 g. Thesolution was filtered through a 0.20-μm membrane filter (MILLEX(trademark) LG SLLGH13NH; Merck Millipore) and placed in an amount of 1g into a 5-mL glass vial, and then half stoppering was performed with arubber top. The vial filled with the solution was set inside alyophilizer (DFM-05B-S; ULVAC) and cooled under atmospheric pressure for1 hour, with the shelf temperature of the lyophilizer set to 5° C.Afterward, the shelf temperature of the lyophilizer was lowered to −40°C. over a 1 hour period, thereby causing the solution to freeze, andthis temperature was maintained for 3 hours. Subsequently, the pressureinside the lyophilizer was set to approximately 10 Pa, and the shelftemperature of the lyophilizer was raised to −10° C. over a 6 hourperiod, after which this state was maintained for 30 hours. The pressureinside the lyophilizer was then set below 10 Pa, the shelf temperatureof the lyophilizer was raised to 25° C. over a 7 hour period, and thisstate was maintained for 15 hours. After completion of drying, thepressure inside the lyophilizer was reverted to atmospheric pressureusing nitrogen gas, and full stoppering was performed with a rubber top.The vial was taken out of the lyophilizer, and an aluminum cap wasscrewed on to obtain a lyophilized composition in which compound (I) iscrystalline form I. It may be added that the sodium chloride used was ofspecial grade and was purchased from Nacalai Tesque.

Example 1b

600 mg of compound (I) and 129.7 mg of sodium chloride were dissolvedinto distilled water, and the total weight was adjusted to 6 g. Thesolution was filtered through a 0.20-μm membrane filter (MILLEX(trademark) LG SLLGH13NH; Merck Millipore) and placed in an amount of 1g into a 5-mL glass vial, and then half stoppering was performed with arubber top. The vial filled with the solution was set inside alyophilizer (Console 12-3-ST-CR; VirTis) and cooled under atmosphericpressure for 1 hour, with the shelf temperature of the lyophilizer setto 5° C. Afterward, the shelf temperature of the lyophilizer was loweredto −40° C. over a 2.5 hour period, thereby causing the solution tofreeze, and this temperature was maintained for 1 hour. Subsequently,the shelf temperature of the lyophilizer was raised to −4° C. over a 0.5hour period, and this temperature was maintained for 15 hours. The shelftemperature of the lyophilizer was then lowered to −40° C. over a 2 hourperiod, thereby causing the solution to freeze again, and thistemperature was maintained for 0.5 hours. Subsequently, the pressureinside the lyophilizer was set below 10 Pa, the shelf temperature of thelyophilizer was raised to −10° C. over a 0.5 hour period, and this statewas maintained for 20 hours. The shelf temperature of the lyophilizerwas then raised to 25° C. over a 0.5 hour period, and this state wasmaintained for 3 hours. After completion of drying, the pressure insidethe lyophilizer was reverted to atmospheric pressure and full stopperingwas performed with a rubber top. The vial was taken out of thelyophilizer, and an aluminum cap was screwed on to obtain a lyophilizedcomposition in which compound (I) is crystalline form I.

Example 2 Crystalline form I of Compound (I) Example 2a

1.0 g of crystalline form III of compound (I) was dissolved in 10 mL ofdeionized water. 0.18 g of sodium chloride was added to the obtainedsolution and dissolved therein at ambient temperature. This solution wascooled to 0° C. and then finely filtered. To the filtrate was addeddropwise 45 mL of chilled isopropanol for over 1 hour, followed bystirring overnight. The resulted crystals were isolated, and dried underreduced pressure at ambient temperature for 0.5 hour to afford 0.82 g ofcrystals of compound (I) (yield=82.0%, crystalline form I).

Example 2b

After dissolving 1.71 g of sodium chloride in 100 mL of deionized water,10 g of compound (I) was added and dissolved at ambient temperature.This solution was cooled to 0 to 5° C. and finely filtered. Then, to thefiltrate 50 mg (0.5 wt %) of crystalline form I of compound (I) obtainedin Example 2a was added and stirred for 1 hour at 0 to 5° C. 500 mL ofchilled isopropanol was added dropwise for over 1 hour, stirredovernight, and then crystals were isolated. The obtained crystals weredried under reduced pressure at ambient temperature for 0.5 hour toafford 9.53 g of crystals of compound (I) (yield=94.8%, crystalline formI).

Comparative Example 1 A Lyophilized Composition of Compound (I)

This comparative example was prepared using the same procedure asExample 1 except that no sodium chloride was incorporated. Specifically,700 mg of compound (I) was dissolved into distilled water, and the totalweight was adjusted to 7 g. The solution was filtered through a 0.20-μmmembrane filter (MILLEX (trademark) LG SLLGH13NH; Merck Millipore) andplaced in an amount of 1 g into a 5-mL glass vial, and then halfstoppering was performed with a rubber top. The vial filled with thesolution was set inside a lyophilizer (DFM-05B-S; ULVAC) and cooledunder atmospheric pressure for 1 hour, with the shelf temperature of thelyophilizer set to 5° C. Afterward, the shelf temperature of thelyophilizer was lowered to −40° C. over a 1 hour period, thereby causingthe solution to freeze, and this temperature was maintained for 3 hours.Subsequently, the pressure inside the lyophilizer was set toapproximately 10 Pa, the shelf temperature of the lyophilizer was raisedto −10° C. over a 6 hour period, and this state was maintained for 30hours. The pressure inside the lyophilizer was then set below 10 Pa, theshelf temperature of the lyophilizer was raised to 25° C. over a 7 hourperiod, and this state was maintained for 15 hours. After completion ofdrying, the pressure inside the lyophilizer was reverted to atmosphericpressure using nitrogen gas, and full stoppering was performed with arubber top. The vial was taken out of the lyophilizer, and an aluminumcap was screwed on to obtain a lyophilized composition in which compound(I) is amorphous.

Comparative example 2 Crystalline form I of compound (I) (a producingmethod using an octadecylsilica gel or resin column purification)

Comparative Example 2a

A 0.5 M acetate buffer (pH 5.5, 35 mL) was ice-cooled, and to this wereadded compound (I) (36 g) and cooled 5M aqueous sodium hydroxidesolution alternately to adjust the pH to 5.5. The mixture was subjectedto octadecylsilica gel column chromatography (3.6 L) and eluted withwater. Active fractions were collected and concentrated under reducedpressure with a water bath of 35° C. The precipitated crystals weredried in vacuo overnight. 2.10 g of the resulting crystals waspulverized, and then isopropanol/water (19/1, 13 mL) was added underice-cooling, followed by stirring at 0° C. for 1 hour. The suspensionwas filtered, followed by washing with cooled isopropanol/water (19/1,80 mL). The resulting crystals were dried in vacuo to afford 1.68 g ofcrystalline form I of compound (I) (yield 80%). DSC endothermic peak:111° C. Solubility in an aqueous 60% isopropanol solution: 0.44% (10°C.), 0.48% (20° C.).

Comparative Example 2b

Compound (I) (net 4.253 g) was dissolved in a 0.2 M phosphate buffer (pH6.5, 73 mL) and the pH was adjusted to 5.5, followed by dilution withwater (20 mL). The mixture was concentrated to 130 mL, subjected toresin purification (SP207, 260 mL), and eluted with water (238 mL) andan aqueous 10% isopropanol solution (780 mL). Active fractions werecollected and concentrated to 30 mL under reduced pressure. To this wasintroduced activated carbon (Seisei Shirasagi, 87 mg), followed bystirring at room temperature for 30 minutes. The activated carbon wasfiltered off with a membrane filter, and the filtrate was subjected tolyophilization to afford 4.07 g of compound (I) in an amorphous form(yield 95.7%). This amorphous compound (I) (0.2 g) was dissolved inwater (0.8 mL), and the solution was added isopropanol (1.2 mL) andseeded with crystalline form I (Comparative example 2a, 1 mg) at roomtemperature, followed by stirring with a stirring bar for 3 hours. Theprecipitated crystals were filtered and dried to afford 0.1 g ofcrystalline form I of compound (I) (yield 50%).

Comparative Example 2c

Compound (I) (net 2.113 g) and a 0.2 M phosphate buffer (pH 6.5, 73 mL)were added alternately, and the pH was adjusted to 4.6, followed bydilution with water (27 mL). The mixture was concentrated to 80 mL underreduced pressure, and then the pH was adjusted to 5.4 with a 0.2 Mphosphate buffer (pH 6.5, 16 mL), followed by dilution with water (48mL). The mixture was subjected to resin purification (SP207, 240 mL),and eluted with water (276 mL) and an aqueous 10% isopropanol solution(720 mL). Active fractions were collected and concentrated under reducedpressure to 12 mL. To this was added activated carbon (Seisei Shirasagi,40 mg), followed by stirring at room temperature for 30 minutes. Theactivated carbon was filtered off through a membrane filter, followed bydilution with water to 14 mL. The aqueous solution was seeded withcrystalline form I (Example 2b, 6 mg), stirred with a stirring bar atroom temperature. To the resulting suspension was added dropwiseisopropanol (84 mL) over 1 hour. After completion of dropwise addition,the mixture was stirred for 3 hours. The precipitated crystals werefiltered and dried to afford 1.834 g of crystalline form I of compound(I) (yield 86.8%). Water content: 5.37%, the content of anhydrousproduct: 95.3%, HPLC area ratio of 99.3%.

Test Example 1 Powder X-ray Diffraction Measurements

Powder X-ray diffraction measurements were performed for the lyophilizedcompositions obtained in Example 1a, Example 1b and Comparative example1, the crystals obtained in Example 2a and Example 2b, the crystalsobtained in Comparative Example 2a, Comparative Example 2b andComparative Example 2c, and sodium chloride using a powder X-raydiffractometer (RINT2200; Rigaku), under the following conditions.

<Measurement Conditions>

-   X-ray: Cu (40 kV, 40 mA)-   Sample rotation: 60 rpm-   Divergence slit: 0.5°-   Scattering slit: 0.5°-   Receiving slit: 0.3 mm-   Monochromator receiving slit: 0.8 mm-   Sampling width: 0.02°-   Detector: scintillation counter-   Scanning speed: 1°/min-   Scanning range: 5°-40°

The X-ray diffractograms for Example 1a, Example 1b, Example 2b,Comparative example 1 and sodium chloride are shown in FIGS. 1, 2, 3, 4and 5, respectively. The lyophilized compositions obtained in Examples1a and 1b were crystalline while the lyophilized composition obtained inComparative example 1 was amorphous. Further, it was confirmed that thecrystals of Example 2b were crystalline form I of compound (I) in viewof the X-ray diffractgram thereof. Likely, it was confirmed that thecrystals of Example 2a and Comparative examples 2a to 2c were alsocrystalline form I of compound (I) in view of the X-ray diffractogramsthereof, but the data were not shown.

Considering that the same crystalline form I of compound (I) wereobtained in any of Examples 2a and 2b as well as Comparative examples 2ato 2c, it was demonstrated that crystalline form I can be predominantlyproduced by crystallization from an aqueous solution containing sodiumchloride without passing through purification with octadecylsilica gelcolumn chromatography or resin performed in Comparative examples 2a to2c.

A peak was observed at 31 to 32° in the X-ray diffractograms forExamples 1 a and 1b, but the peak was absent in Example 2b. Consideringthat a peak was observed at 31 to 32° in the X-ray diffractogram forsodium chloride (FIG. 5), it is understood that this peak was caused bysodium chloride contained in the lyophilized compositions. Since anaqueous solution containing compound (I) and an inorganic salt islyophilized in the present invention, the obtained lyophilizedcomposition obviously contains the inorganic salt. Since the patternexcept the peak at 31-32° of the X-ray diffractogram for Examples 1a and1b matches the pattern of Example 2b, it was confirmed that crystalsobtained in Examples 1a and 1b were also crystalline form I. On theother hand, after checking amounts of sodium ion and chloride ioncontained in crystalline form I obtained in Example 2b with ionchromatography, both of the amounts were 0.1% or less.

In the present invention, although compound (I) is crystallized from anaqueous solution containing compound (I) and an inorganic salt, it wasconfirmed that the obtained crystals of compound (I) does not containthe inorganic salt.

Test Example 2 Stability Evaluation

The crystals obtained in Examples 1a and 1b, and the amorphouslyophilized composition obtained in Comparative example 1 were subjectedto stress tests at 60° C. (2 weeks and 1 month) using a temperature andhumidity test chamber (LH2O-12M; Nagano Science), and then relatedsubstances were measured by HPLC under the following conditions.

<Testing Conditions>

-   -   Column: Waters Atlantis dC18, 5 μm, 4.6×250 mm    -   Column temperature: maintained constant at about 35° C.    -   Injection volume: 5 μL    -   Detector: UV absorption photometer (Measured wavelength: 210 nm)    -   Mobile phase A: 1.32 g of diammonium hydrogen phosphate was        dissolved into 900 mL of water, to which was added phosphoric        acid to adjust the pH to 3.0, and the total volume was adjusted        to 1000 mL with water.    -   Mobile phase B: acetonitrile for liquid chromatography    -   Gradient program: The mixing ratio of mobile phases A and B was        controlled to change in the following manner.

Time after Mobile phase Mobile phase injection (min) A (vol %) B (vol %)0-5 100  0  5-20 100 → 90 0 → 10 20-30  90 10

-   -   Flow rate: 1.0 mL/min    -   Retention time of compound (I): Approximately 6.5 min    -   Measurement time: 30 min

Changes in the total amount of related substances for each sample wereshown in Table 2. The crystalline lyophilized compositions containedlower amounts of related substances in the initial state than theamorphous lyophilized composition. Moreover, there was, after the stresstests, a considerable increase in the amount of related substancespresent in the amorphous lyophilized composition, whereas increases inthe amounts of related substances were lower for the crystallinelyophilized compositions. These results confirmed that turning compound(I) into a crystalline lyophilized composition using a method of thepresent invention produces a marked improvement in storage stability.

TABLE 2 Total amount of related substances (%) 60° C. 60° C.Crystallinity Initial state 2 weeks 1 month Example 1a Crystalline 0.251.30 0.98 Example 1b Crystalline 0.30 0.50 0.55 Comparative Amorphous0.56 15.07 24.54 example 1

Reference Example 1 Method for Producing Compound (I) Reference Example1atert-Butyl{2-[({[(2S,5R)-6-benzyloxy-7-oxo-1,6-diazabicyclo[3.2.1]oct-2-yl]carbonyl}amino)oxy]ethyl}carbamate

A solution of(2S,5R)-6-(benzyloxy)-7-oxo-1,6-diazabicyclo[3.2.1]octane-2-carboxylicacid (4.80 kg, 17.373 mol) in dehydrated ethyl acetate (62 L) was cooledto −30° C., to which isobutyl chloroformate (2.52 kg) and thentriethylamine (1.85 kg) were added dropwise, and was stirred at −30° C.for 15 minutes. To the reaction mixture was added a solution oftert-butyl 2-(aminooxy)ethylcarbamate in dehydrated ethyl acetate (15 wt%, 23.45 kg) over 30 minutes (the residue washed with 2 L of dehydratedethyl acetate), and the temperature was raised to 0° C. over 1 hour. Themixture was washed sequentially with an 8% solution of citric acid (65L), a 5% solution of sodium bicarbonate (60 L), and water (60 L), andconcentrated to 24 L. A step of adding ethyl acetate (24 L) to theconcentrated mixture, followed by concentration to 24 L for solventdisplacement was performed twice, and to the resultant concentratedsolution, ethyl acetate (29 L) and hexane (72 L) were added, and stirredovernight. To the mixture, hexane (82 L) was added dropwise and stirredfor 2 hours. The precipitated crystals were separated by filtration,washed with hexane, and vacuum-dried to give 5.51 kg of the titlecompound (yield 76%).

-   HPLC:COSMOSIL 5C18 MS-II 4.6×150 mm, 33.3 mM phosphate    buffer/MeCN=50/50, 1.0 mL/min, UV 210 nm, RT 4.4 min; ¹H NMR (400    MHz, CDCl₃) δ 1.44 (s, 9H), 1.56-1.70 (m, 1H), 1.90-2.09 (m, 2H),    2.25-2.38 (m, 1H), 2.76 (d, J=11.6 Hz, 1H), 3.03 (br.d., J=11.6 Hz,    1H), 3.24-3.47 (m, 3H), 3.84-4.01 (m, 3H), 4.90 (d, J=11.6 Hz, 1H),    5.05 (d, J=11.6 Hz, 1H), 5.44 (br.s., 1H), 7.34-7.48 (m, 5H), 9.37    (br.s., 1H); MS m/z 435 [M+H]⁺.

Reference Example 1b tert-Butyl{2-[({[(2S,5R)-6-hydroxy-7-oxo-1,6-diazabicyclo[3.2.1]oct-2-yl]carbonyl}amino)oxy]ethyl}carbamate

To a solution of tert-butyl {2-[({[(2S,5R)-6-benzyloxy-7-oxo-1,6-diazabicyclo[3.2.1]oct-2-yl]carbonyl}amino)oxy]ethyl}carbamate(5.52 kg, 12.705 mol) in methanol (85 L), a 10% palladium-carboncatalyst (50% water, 0.55 kg) was added and stirred under hydrogenpressure (0.1 MPa) for 1 hour. The catalyst was filtered off and thesolid was washed with methanol (25 L). The filtrate and wash werecombined and concentrated under reduced pressure to 39 L at a solutiontemperature below 10° C. A step of adding acetonitrile (44 L) to theconcentrated mixture, followed by concentration to 39 L at a solutiontemperature below 10° C. for solvent displacement was performed twice,and the mixture was cooled to 0° C. and stirred overnight. Theprecipitated crystals were separated by filtration, washed withacetonitrile (24 L), and vacuum-dried to give 3.63 kg of the titlecompound (yield 83%).

-   HPLC:COSMOSIL 5C18 MS-II 4.6×150 mm, 33.3 mM phosphate    buffer/MeCN=75/25, 1.0 mL/min, UV 210 nm, RT 3.9 min; ¹H NMR (400    MHz, CD₃OD) δ 1.44 (s, 9H), 1.73-1.83 (m, 1H), 1.86-1.99 (m, 1H),    2.01-2.12 (m, 1H), 2.22 (br.dd., J=15.0, 7.0 Hz, 1H), 3.03 (d,    J=12.0 Hz, 1H), 3.12 (br.d., J=12.0 Hz, 1H), 3.25-3.35 (m, 2H),    3.68-3.71 (m, 1H), 3.82-3.91 (m, 3H); MS m/z 345 [M+H]⁺.

Reference Example 1c Tetrabutylammonium tert-butyl {2-[({[(2S,5R)-7-oxo-6-(sulfooxy)-1,6-diazabicyclo[3.2.1]oct-2-yl]carbonyl}amino)oxy]ethyl}carbamate

To acetonitrile (51 L) were sequentially added water (51 mL), tert-butyl{2-[({[(2S,5R)-6-hydroxy-7-oxo-1,6-diazabicyclo[3.2.1]oct-2-yl]carbonyl}amino)oxy]ethyl}carbamate(3.53 kg, 10.251 mol), sulfur trioxide-pyridine complex (3.95 kg), and2,6-lutidine (2.21 kg), and stirred at 35 to 45° C. overnight. Themixture was filtered to remove the insoluble matter, the solid waswashed with acetonitrile (11 L) and the filtrate and wash were combinedand concentrated to 17 L. The concentrated solution was cooled to below10° C., to which were added a 9% aqueous solution of sodiumdihydrogenphosphate (60 L) and ethyl acetate (113 L) to effect phaseseparation, and the organic layer was extracted again with a 9% aqueoussolution of sodium dihydrogenphosphate (11 L). To the aqueous layerobtained were added ethyl acetate (113 L), a 30% aqueous solution oftetrabutylammonium hydrogen sulfate (12.87 kg), and a 37% aqueoussolution of sodium dihydrogenphosphate (56.5 kg), and stirred for 15minutes. The organic layer was separated, washed with a 20% aqueoussolution of sodium dihydrogenphosphate (60 L), dried over anhydrousmagnesium sulfate (2.5 kg), filtered, and then concentrated underreduced pressure. Crystals of the title compound deposited in theconcentrated solution were dissolved into ethyl acetate, and the totalvolume was adjusted to 20 L to yield 32.55 kg of a solution of the titlecompound in ethyl acetate (net 6.25 kg, yield 92%). This solution wasused in the next step without further purification.

Reference Example 1d Crude Compound (I)

A solution of tetrabutylammonium tert-butyl {2-[({[(2S,5R)-7-oxo-6-(sulfooxy)-1,6-diazabicyclo[3.2.1]oct-2-yl]carbonyl}amino)oxy]ethyl}carbamate(788 g, net 467.1 g, 0.701 mol) in dichloromethane (934 mL) was cooledto −20° C. in a nitrogen stream, to which trifluoroacetic acid (934 mL)was added dropwise over 15 minutes, and the temperature was raised to 0°C., followed by stirring for 1 hour. The reaction mixture was cooled to−20° C., to which diisopropyl ether (4.17 L) was added dropwise, afterwhich the temperature of the mixture was raised to −6° C., followed bystirring for 1 hour. The precipitate was filtered, washed by suspensionin diisopropyl ether (2×1 L), and the wet solid was vacuum-dried to give342.08 g of the title compound (net 222.35 g, yield 98%, HPLC area ratio96.1%, CE/TFA 27 mol %).

Reference Example 1e

0.2 M phosphate buffer (pH 6.5, 7.2 L) was cooled to below 10° C., towhich(2S,5R)-N-(2-aminoethoxy)-7-oxo-6-(sulfooxy)-1,6-diazabicyclo[3.2.1]octane-2-carboxamide(the crude compound (I) in Reference example 1d, net 1.2 kg) andice-cold 0.2 M phosphate buffer (pH 6.5, 3.5 L) were added alternatelyportionwise while stirring in a manner in which the pH remained between4.2 and 4.8, and the final pH was adjusted to 4.6. The mixture wasdiluted with water (19.3 L) (total quantity 30 L), and concentrated to24 L under reduced pressure at solution temperatures below 18° C. Afterthe pH of the concentrated solution was adjusted to 5.4 with 0.2 Mphosphate buffer (pH 6.5, 2.4 L), the concentrated solution was dilutedwith water to 43.2 L and purified using a resin (Sepabeads SP207, 75 L),where water (83 L) and a 10% aqueous solution of isopropanol were usedfor elution and active fractions were collected. The active fractionswere combined (33 L), concentrated to 7.2 L at solution temperaturesbelow 15° C., to which was added activated carbon (24 g), followed bystirring for 30 minutes. The activated carbon was filtered off through amembrane filter, and washed with water (0.4 L×2). The filtrate and washwere combined and after the temperature of the solution was adjusted to20 to 25° C., crystalline form III (3.6 g) obtained according to amethod mentioned in Example 7a of Patent Document 6 were inoculated. Tothe mixture, isopropanol (50.4 L) was added dropwise over 1 hour, andstirred overnight. The crystals deposited were filtered, washed withisopropanol (4.8 L) and vacuum-dried until the temperature of the wetcrystals reached 20° C., to yield 1.17 kg of crystalline form III ofcompound (I) (yield 90%).

INDUSTRIAL APPLICABILITY

According to the present invention, crystals, especially a singlecrystalline form, and in particular stable crystalline form I ofcompound (I) can be produced easily in an industrial scale, and furtherthe present invention provides a lyophilized composition of compound(I), and especially a single crystalline form and in particularcrystalline form I thereof, having good storage stability and thereforeprovides a useful method for producing injections and the like ofcompound (I).

1. A process for producing crystals of a compound represented by thefollowing formula (I):

comprising crystallizing the compound from an aqueous solutioncontaining the compound and an inorganic salt.
 2. The process accordingto claim 1, wherein a crystalline form I of the compound havingcharacteristic peaks appearing at a lattice spacing (d) of 7.34, 5.66,5.53, 5.30, 5.02, 4.66, 4.37, 4.28, 4.06, 3.68, 3.62, 3.47, 3.36, 3.30,3.16, 3.11, 3.03, 2.99 and 2.50 Å in a powder X-ray diffraction patternis produced.
 3. The process according to claim 1, wherein the aqueoussolution containing the compound and an inorganic salt is obtained bydissolving the compound and the inorganic salt together in water, or bydissolving either of the compound or the inorganic salt in water andthen dissolving the other in the resultant solution.
 4. The processaccording to claim 1, wherein the compound is crystallized by adding apoor solvent to the aqueous solution containing the compound and theinorganic salt.
 5. The process according to claim 4, wherein the poorsolvent is an alcohol.
 6. The process according to claim 1, wherein thecompound is crystallized by subjecting the aqueous solution containingthe compound and the inorganic salt to lyophilization.